A common type of railroad freight car in use today is an open-top hopper car wherein lading carried by the hopper car is discharged through openings provided on an underside or bottom of the car. Such cars are used to transport numerous types of lading including aggregate, iron ore and other types of lading. Such cars offer an advantageously economical method of transporting large amounts of lading between distant locations.
Such railroad cars generally include a walled enclosure or hopper carried on an underframe of the railcar. On some railroad hopper cars, the underframe includes a longitudinally elongated centersill or support which defines a longitudinal axis for the railcar. Toward opposed ends thereof, the centersill is carried by the usual wheeled trucks which ride on tracks or rails. Although the design of the bottom of the railcar varies considerably, the hopper is typically provided with a plurality of generally funnel-shaped chutes which extend either parallel to the longitudinal axis of the railcar (longitudinal openings) or are disposed in pairs on opposite lateral sides of the longitudinal axis of the railcar (transverse openings). The generally funnel-shaped chute terminates in a discharge opening through which lading is gravitationally discharged from the railcar. Each type of hopper serves a particular need in the railroad industry.
To control the discharge of lading from the hopper, a door is provided in registry with either both or each discharge openings on the railcar. Typically, the discharge door is hinged toward an upper end thereof to the railcar such that, when released, the door gravitationally swings toward an open position assisted by columnar load of the lading gravitationally pushing down on and moving through each discharge opening.
Different types of door operating mechanisms are known in the prior art. It is important to note, however, such door operating mechanism are specifically designed to the particular operation with which they will find utility. For example, a mechanism used to operate longitudinally mounted doors cannot, without significant redesign, be used to operate transversely arranged doors and vice versa. Moreover, and primarily because of the disposition of the door relative to the longitudinal axis of the railcar, mechanisms used to operate longitudinally mounted doors usually require a powered operated driver to move the doors between closed and open positions. As will be appreciated, requiring a powered operated driver to operate such mechanism increases the overall cost of the railcar. Of course, increasing any manufacturing costs is adverse to railcar manufacturers. Thus, those mechanisms used to operate longitudinally mounted doors do not and are not useful with those hopper cars having transversely mounted doors for selectively controlling the discharge of lading from the hopper.
Designing a mechanism for operating one or more transversely mounted doors on a railroad hopper car also has design challenges. In hopper cars of the identified type having the doors extending transversely of the hopper car, a generally accepted method of maintaining the doors in the closed position involves the employment of independently functioning latching mechanism on opposed sides of the hopper car. Previously known latching mechanisms include a pivotable hook that is actually a double hook in that it has a small recess which engages with a device to hold the door in a “catch” position and one larger recess to hold the door in a fully closed position. Two operators or workmen generally work together on opposite sides of the railcar and swing the open laterally adjacent doors from the fully open position to the “catch” position by pushing with one foot on the respective doors. In the “catch” position, the doors remain open a few inches at their lower end. Each workman next places a long pry bar , usually about 5 foot long and about 1.5 inches in diameter, to lever the door to a fully closed position whereupon the larger recess on each hook drops in to its working position. In operation, this mechanism has been known to fail to maintain the doors in their closed position. Moreover, and as will be appreciated, unless the locks are positively operated in unison relative to each other, additional problems can and do arise, That is, there is significant columnar load placed on beach door by the lading in the hopper of the railcar. Although the transversely disposed doors are typically joined by an elongated connector or spreader bar, opening one lock without opening the other lock can cause the door to twist about its upper pivot thus possibly resulting in door distortion problems.
Both the length and width of each discharge opening defined toward the lower end of each hopper chute must be sufficiently sized to substantially prevent lading from bridging over the discharge outlet so as to facilitate the discharge of lading from the hopper car. Accordingly, the door arranged in operable combination with such discharge opening must be sized to cover the entire opening when the door is in the closed position. As such, the weight of the door is substantial, thus, adding to the effort required of the operator to close the door from the open position. Considering there are up to four sets of transversely mounted doors on each hopper rail car which are all required to be manually closed after the lading is discharged therefrom, the continuing manual effort required to close the doors is both tedious and tiring.
To unlock this type of prior art door lock, a workman on each side of the railcar drives the respective hook upwards to release the door. Sometimes the hook stays up momentarily, permitting the door to move to the fully open position. At other times, the hook may drop earlier in time to hold the door in the “catch” position, in which case, the workmen is required to hammer the hook upward to release the door to a fully open position. The hook is operated primarily by gravity, making the operation thereof somewhat dependent upon the particular orientation of the hopper car and the freedom with which the hook pivots about its pivot pin.
As mentioned, the bottom of the railcar is typically designed to have several funnel-shaped chutes disposed between opposed ends the railcar. Accordingly, the spacings between longitudinally adjacent chutes wherein the operating mechanism for such doors is to be located is extremely limited. As will be appreciated by those skilled in the art, the limited space constraints inherent with hopper cars having transversely mounted doors operable in pairs causes significant design problems.
Thus, there is a need and continuing desire for a mechanism for operating in unison a pair of transversely mounted doors on a railroad hopper car having a centersill.